Development of a Portable and Sensitive CO 2 Measurement Device with NDIR Sensor Clusters and Minimizing Water Vapor Impact

Increasing carbon dioxide (CO 2 ) concentrations threaten human production and life. Currently the equipment used for CO 2 monitoring is heavy and expensive, without a portable CO 2 detector that is inexpensive and resistant to interference. Here we designed a portable CO 2 detector based on no-dispersive infrared sensors to measure CO 2 concentration. The detector, which has a mass of 1 kg, is powered by a lithium battery with dimensions of 200 mm (length) × 150 mm (width) × 100 mm (height). Considering the fact that field observations are susceptible to humidity, a series of experiments were carried out to reduce the humidity interference on sensor responses at a laboratory. The values of humidity and CO 2 variation were used in a regression model analysis to determine a quadratic function with an R 2 above 0.94. The detector was compared with a reference analyzer in ambient CO 2 measurement during a 7-day field campaign in Hangzhou, China. After humidity correction, the data show better correlation with the reference data, with the R 2 0.62–0.97 increasing from 0.62–0.97 compared to before the correction and the value deviation decreasing to less than 3%. Cluster analysis of sensors revealed a reduction in average relative deviation of up to 1.4% as the number of sensors increased.